Support file:// mirrors

Spawns a simple HTTP server to host the mirror.
Useful for testing mirror support or CI in chroot or bwrap modes.

lib/simple_mirror.py

@@ -0,0 +1,14 @@
+import http.server
+import socketserver
+
+class SimpleMirror(socketserver.TCPServer):
+    def __init__(self, directory: str):
+        self.directory = directory
+        super().__init__(("localhost", 0), self._handler)
+
+    @property
+    def port(self):
+        return self.server_address[1]
+
+    def _handler(self, *args, **kwargs):
+        return http.server.SimpleHTTPRequestHandler(*args, directory=self.directory, **kwargs)